1. Field of the Invention
The present invention relates generally to a corner bead for finishing a corner edge of a wall, and more particularly, to a preformed corner bead adapted for quick and simplified placement in an operative position secured along the corner edge, ready for a finishing layer of joint compound or the like to be applied thereto.
2. Description of the Prior Art
In the erection of plaster walls, wallboards or drywall sheets, hereafter referred to generally as drywall, it is known to provide a corner bead along inside and outside corner edges where two sheets of drywall join.
Known corner beads typically comprise rigid strips of steel which have been bent axially into an "L" shape, forming side flanges or shoulders which extend from each other in cross-section at an 90.degree. angle.
In use, the corner beads are manually held along a corner formed by two intersecting sheets of drywall so that the metal flanges overlap the adjacent drywall sheet. Nails are driven through each of the flanges into the drywall sheets, securing the corner bead in place along the corner edge. A covering layer of joint compound, spackle or the like is then applied over the corner bead, and feathered smooth over the flanges with the adjacent drywall to conceal the corner bead and provide a sharply-defined and aesthetically pleasing finished corner.
A difficulty with conventional corner beads is that that the nailing of the corner bead in place is awkward, time consuming and inconvenient.
A further difficulty arises in that the nails used in securing the corner bead to the drywall frequently twist on nailing, with the result that the nail heads do not rest flush against the flanges. The twisting of nails thereby increases the difficulty of the task of covering the nails and corner bead by the overlying layer of joint compound.
To ensure the corner bead provides adequate strength to the corner edge, and to provide a sufficiently wide nailing surface, the flanges of conventional metal corner beads extend in the lateral direction from the axial bend a distance of 1.25 to 2.5 inches. The sizing of conventional corner beads is disadvantageous in that the amount of steel required in manufacture increases both the materials cost, and as well, the weight of the product, adversely affecting the number of corner beads which can be easily carried or shipped.
In an attempt to overcome some of the disadvantages of conventional corner beads, U.S. Pat. No. 5,131,198 to Ritchie et al., which issued Jul. 21, 1992, discloses a composite corner bead having paper flanges which are attached by a heat melted adhesive to a metal core member. The corner bead disclosed in U.S. Pat. No. 5,131,198, however, continues to suffer the disadvantage that it must be manually held and then nailed in place prior to the application of the finishing layer of joint compound.
It is also known to secure the composite corner bead shown in U.S. Pat. No. 5,131,198 along a wall corner by the use of joint compound or the like. The use of the paper composite corner bead together with joint compound is disadvantageous in that a special tool or applicator box is required to roll into the corner bead a V-shaped layer of joint compound approximately 1/8 inch thick.
The applicant has considered precoating a corner bead with a layer of glue or adhesive, in a similar manner as the plastic corner edge protecting guard disclosed in U.S. Pat. No. 4,012,878 to Elligson, issued Mar. 22, 1977. There exists the difficulty that a corner bead precoated with a conventional adhesive would require preliminary preparation prior to its placement. For example, such preliminary preparation may include the wetting of a preapplied dry adhesive, to tackify the adhesive. Alternately a covering release sheet which has been applied over a preactivated adhesive may be removed. Corner beads precoated with a conventional adhesive in the manner of U.S. Pat. No. 4,012,878 would, however, suffer the disadvantages of increased inconvenience and waste, as well as increased manufacturing difficulties. A further disadvantage in providing a corner bead precoated with a conventional adhesive is that the adhesive would tend to bond the corner bead to the drywall immediately and permanently on contact therewith. The immediate bonding of the corner bead to the drywall would therefore prevent movement of the corner bead to permit its adjustment to a final optimal position over the corner edge.